Einfluss unterschiedlicher Bewirtschaftungsverfahren auf P-Formen und P-Dynamik im Boden

Summary

The impact of cropping systems on soil phosphorus (P) forms and P dynamics was
studied. The systems were a biodynamic (DYN), a bioorganic (BIO), a conventional
(CON), a stockless system (MIN) and an unfertilized control (NON). These cropping
systems are part of the DOK field trial in Therwil near Basel. The systems differed in
fertilization and plant protection. The P budgets over 30 years were negative except
for CON and increased in the order: NON < DYN < ORG < MIN < CON. A sequential
P extraction scheme was used to characterize the P forms in soil samples from 2007
and 1977 (before the start of the trial). Labile inorganic P (Pi) forms differed significantly
between cropping systems. Organic P forms (Po) and stable Pi forms were not
affected by the cropping systems apart from Po in concentrated HCl extract. The
comparison between P forms in the soils of 2007 and 1977 revealed depletion in labile
Pi forms in all systems. The changes were related to the P budget. Po changes were
small and thus most of Po appears to be strongly stabilized in the soil.